The continuing miniaturization of electronic circuits in recent years has resulted in many new applications for electronic circuits as more and more complex electronic circuits can be accommodated in ever more decreasing space. Also identification systems have undergone significant changes due to the progress in the VLSI of electronic circuits. Moreover, two new concepts have recently been introduced for improving identification systems.
The first one is the idea of a wearable electronic key, which is described in an article by Noboyuki Matushita, Shigeru Tajima, Yuji Ayatsuka, Jun Rekimoto with the title “Wearable Key: Device for Personalizing nearby Environment” which was presented on the Fourth International Symposium on Wearable Computers (ISWC 2000).
The second one is the so-called intra-body communication, which is in general described in an article by Kurt Partridge, Mike Sinclair, Gaetano Boriello, Turner Whitted titled “Sending Signals through Skin: Applications and Advantages”. U.S. Pat. No. 6,754,472 discloses a communication system that uses capacitive coupling to transmit power and data through a user's body.
With respect to a clinical environment, there has always been the need for a reliable patient identification system. Such system for automatic, continuous and reliable electronic patient identification has been developed by combining these new concepts which allows a body-worn identification device that continuously broadcasts the patient identifier through intra-body communication. According to this electronic patient identification system, a patient wears an electronic key containing identification data ID which are transmitted via intra-body communication when the patient gets into contact with a target device so that a capacitive coupling is possible. The wearable electronic key containing the identification data of the patient can be integrated in, for example, a wristwatch of the patient is wearing, which provides a direct contact of the key with the patient's skin.
Wearable electronic ID keys in conjunction with intra-body communication enable users to authorize themselves in a convenient and intuitive way. The wearable key regularly transmits the user's ID through the human body. Thereby all devices in contact with the user's body can receive the user's ID. This enables users to personalize a device or to authorize, for example, a payment simply by touch.
Although intra-body communication is relatively secure against eavesdropping since the communication is restricted to the human body (contrary, for example, to radio communication with a range of a typically 10 meter (Bluetooth) to 50 meters (wireless LAN)), there is a weak point: an intruder can pretend to be someone else by simply touching (or even just coming very close (e.g. 5 cm) to his victim and touching the target device he wants to deceive. This deceit is called “man-in-the-middle attack”.
Therefore, without counter measures, the wearable electronic key concept is not acceptable for access control, authorizing payment and business transactions and the like.